Beverage preparation machines are well known in the food science and consumer goods area. Such machines allow a consumer to prepare at home a given type of beverage, for instance a coffee-based beverage, e.g. an espresso or a brew-like coffee cup.
Today, most beverage preparation machines for in-home beverage preparation comprise a system made of a machine which can accommodate portioned ingredients for the preparation of the beverage. Such portions can be soft pods or pads, or sachets, but more and more systems use semi-rigid or rigid portions such as rigid pods or capsules. In the following, it will be considered that the beverage machine of the invention is a beverage preparation machine working with a rigid or semi-rigid capsule.
The machine comprises a receptacle or cavity for accommodating said capsule and a fluid injection system for injecting a fluid, preferably water, under pressure into the capsule. Water injected under pressure in the capsule, for the preparation of a coffee beverage according to the present invention, is preferably hot, that is to say at a temperature above 70° C. However, in some particular instances, it might also be at ambient temperature, or even chilled. The pressure inside the capsule chamber during extraction and/or dissolution of the capsule contents is typically about 1 to about 8 bar for dissolution products and about 2 to about 12 bar for extraction of roast and ground coffee. Such a preparation process differs a lot from the so-called “brewing” process of beverage preparation—particularly for tea and coffee, in that brewing involves a long time of infusion of the ingredient by a fluid (e.g. hot water), whereas the beverage preparation process allows a consumer to prepare a beverage, for instance coffee, within a few seconds.
The principle of extracting and/or dissolving the contents of a closed capsule under pressure is known, and consists typically of inserting the capsule in a receptacle or cavity of a machine, injecting a quantity of pressurized water into the capsule, generally after piercing a face of the capsule with a piercing injection element such as a fluid injection needle mounted on the machine, so as to create a pressurized environment inside the capsule either to extract the substance or dissolve it, and then release the extracted substance or the dissolved substance through the capsule. Capsules allowing the application of this principle have already been described for example in applicant's European patents no EP 1472156 B1, and EP 1784344 B1.
Machines allowing the application of this principle have already been described for example in patents CH 605 293 and EP 242 556. According to these documents, the machine comprises a receptacle or cavity for the capsule and a perforation and injection element made in the form of a hollow needle comprising in its distal region one or more liquid injection orifices. The needle has a dual function in that it opens the top portion of the capsule on the one hand, and that it forms the water inlet channel into the capsule on the other hand.
The machine further comprises a fluid tank—in most cases this fluid is water—for storing the fluid that is used to dissolve and/or infuse and/or extract under pressure the ingredient(s) contained in the capsule. The machine comprises a heating element such as a boiler or a heat exchanger, which is able to warm up the water used therein to working temperatures (classically temperatures up to 80-90° C.). Finally, the machine comprises a pump element for circulating the water from the tank to the capsule, optionally though the heating element. The way the water circulates within the machine is e.g. selected via a selecting valve means, such as for instance a peristaltic valve of the type described in applicant's European patent application EP 2162653 A1.
When the beverage to be prepared is coffee, one interesting way to prepare the coffee is to provide the consumer with a capsule containing roast and ground coffee powder, which is to be extracted with hot water injected therein.
In many instances, the machine comprises a capsule holder for holding a capsule, which is intended to be inserted in and removed from a corresponding cavity or receptacle of the machine. When a capsule holder is loaded with a capsule and inserted within the machine in a functional manner, the water injection means of the machine can fluidly connect to the capsule to inject water therein for a food preparation, as described above. A capsule holder was described for example in applicant's European patent EP 1967100 B1.
Capsules have been developed for such an application of food preparation, and in particular for beverage preparation, which are described and claimed in applicant's European patent EP 1784344 B1, or in European patent application EP 2062831.
In short, such capsules comprise typically:                a hollow body and an injection wall which is impermeable to liquids and to air and which is attached to the body and adapted to be punctured by e.g. an injection needle of the machine,        a chamber containing a bed of roast and ground coffee to be extracted, or a soluble ingredient or mix of soluble ingredients,        an aluminium membrane disposed at the bottom end of the capsule, closing the capsule, for retaining the internal pressure in the chamber.        
The aluminium membrane is designed for being pierced with piercing means that are either integral with the capsule, or located outside of said capsule, for example within a capsule holder of the machine.
The piercing means are adapted for piercing dispensing holes in the aluminium membrane when the internal pressure inside the chamber reaches a certain pre-determined value.
Also, optionally, the capsule can further comprise means configured to break the jet of fluid so as to reduce the speed of the jet of fluid injected into the capsule and distribute the fluid across the bed of substance at a reduced speed.
Capsules of the prior art feature an injection wall or membrane (referred to as top membrane) which is to be pierced by a fluid injection element (e.g. needle) of a beverage preparation machine being part of a fluid system. When fluid is injected in the capsule compartment, a pressure is built up, which serves as an extraction means for extracting and/or dissolving ingredients contained inside the capsule, as described above. Such ingredients can be for instance a bed of roast and ground coffee. Alternatively or in combination with roast and ground coffee, the ingredients can comprise soluble ingredients, such as for instance beverage premixes.
Several systems are currently used for capsule identification by the machine, but the main drawback of existing solutions is the relatively high cost of identification systems and/or complexity and cost of a capsule adapted for such an identification. Such identification systems provide a good solution for automatically setting the machine operating parameters to the appropriate values, that are required for preparing a food product out of the specific ingredient contained in the capsule. Such operating parameters include but are not limited to volume of water to be injected in the capsule for mixing with the ingredient (the injected volume will correspond to the volume of product dispensed to the consumer's cup, minus a small residual volume that stays within the capsule at the end of the brewing cycle). Machine operating parameters also include pressure of the injected water, which varies depending on the ingredient (it is typically lower for soluble products, and higher for extraction of roast and ground coffee powder for instance). Machine parameters also include the temperature of water injected within the capsule, which can be chilled, at ambient temperature, or at a high temperature of about 80 to 90° C.
They include but are not limited to: colour recognition, barcodes, recognition of protrusions, grooves, or other artifacts located at the surface of the capsule, conductivity, resistivity and generally all means known for detection or identification of the capsule by means of an electric current or magnetic field. Furthermore, current identification means are embedded in the capsule, and do not allow to automatically set a food preparation machine to the right operating parameters, with capsules that do not contain a built-in identification code for interacting with the machine.
It is therefore an objective of the present invention to provide a means for use with inexpensive capsules that allows to automatically set the machine to the appropriate operating parameters adapted to the preparation of the specific food ingredient contained in said capsule.